1. Field of the Invention
This invention relates to a system for obstacle avoidance path planning for a multiple-degree-of-freedom mechanism, and more particularly to such a system which enables quick and easy determination of the path of a multiple-degree-of-freedom mechanism such as an autonomous mobile robot or the like moving through a space including obstacles.
2. Description of the Prior Art
Obstacle avoidance is one important problem in the control of a multiple-degree-of-freedom mechanism such as an autonomous mobile robot or the like. Various proposals have been made regarding this problem, including those referred to in "Collision Avoidance Control among Moving Obstacles for a Mobile Robot based on the Fuzzy Reasoning", Journal of the Robotics Society of Japan, Vol. 6, No. 6, December, 1988.
The techniques proposed for obstacle avoidance in this and other papers can be classified into two categories: those based on the potential field method and those based on the search method. The potential field method cannot be expected to provide path optimization owing to the fact that it is difficult to escape from local minima that are fallen into, and also because, even when an obstacle has been recognized to be present on the path of travel, the mobile robot does not change its path to avoid it until it has come close to the obstacle. The search method is further divided into two types. In the first, the mobile robot continues to move generally in the direction of the goal while changing its path whenever it is about to collide with an obstacle. In the second, the problem is replaced by one of finding the minimum network time and the optimum path is determined by investigating every possibility. Like the potential field method, the first method does not guarantee optimization. On the other hand, since the second method requires the direction of travel to be selected from among a large number of candidates every time a branch point is reached, it enlarges the space that has to be searched.